X-Git-Url: http://dolda2000.com/gitweb/?a=blobdiff_plain;f=src%2Fcommon.rs;h=283640e87667e53ada0a7ecf6bfb332b98016b5e;hb=98995f2b580d872a5a21b34869fe024fafdf4260;hp=6f000d8762abffc8410b016da5ae28b20c39aa2f;hpb=787dbfb4e03fdc6c6cfdb153e0e8fab2eb3ab2d1;p=kaka%2Frust-sdl-test.git

diff --git a/src/common.rs b/src/common.rs
index 6f000d8..283640e 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -1,8 +1,10 @@
-use std::ops::{Add, AddAssign};
+use std::ops::{Add, AddAssign, Mul};
 
 #[macro_export]
 macro_rules! point {
-    ( $x:expr, $y:expr ) => { Point2D { x:$x, y:$y } };
+    ( $x:expr, $y:expr ) => {
+        Point2D { x: $x, y: $y }
+    };
 }
 
 #[derive(Debug, Copy, Clone, PartialEq)]
@@ -17,11 +19,14 @@ impl Point2D<f64> {
     }
 }
 
-impl<T: Add<Output=T>> Add for Point2D<T> {
+impl<T: Add<Output = T>> Add for Point2D<T> {
     type Output = Point2D<T>;
 
     fn add(self, rhs: Point2D<T>) -> Self::Output {
-        Point2D { x: self.x + rhs.x, y: self.y + rhs.y }
+        Point2D {
+            x: self.x + rhs.x,
+            y: self.y + rhs.y,
+        }
     }
 }
 
@@ -32,6 +37,28 @@ impl<T: AddAssign> AddAssign for Point2D<T> {
     }
 }
 
+#[derive(Default)]
+pub struct Rect<T> {
+    pub width: T,
+    pub height: T,
+}
+
+impl<T: Mul<Output = T> + Copy> Rect<T> {
+    #[allow(dead_code)]
+    pub fn area(&self) -> T {
+        self.width * self.height
+    }
+}
+
+impl<T> From<(T, T)> for Rect<T> {
+    fn from(item: (T, T)) -> Self {
+        Rect {
+            width: item.0,
+            height: item.1,
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -52,4 +79,11 @@ mod tests {
         a += point!(2, 2); // AddAssign
         assert_eq!(a, point!(3, 2));
     }
+
+    #[test]
+    fn area_for_rect_of_multipliable_type() {
+        let r: Rect<_> = (30, 20).into(); // the Into trait uses the From trait
+        assert_eq!(r.area(), 30 * 20);
+        // let a = Rect::from(("a".to_string(), "b".to_string())).area(); // this doesn't work, because area() is not implemented for String
+    }
 }